In recent times, use of secondary batteries have been increased rapidly as power sources for portable electronic appliances, such as personal digital assistants (PDA) and portable multimedia players (PMP); power sources for driving motors of high-output hybrid vehicles, electric vehicles, or the like; and power sources for flexible display devices, such as electronic ink (e-ink), electronic paper (e-paper), flexible liquid crystal display devices (LCD), flexible organic light emitting diodes (OLED), or the like. In addition, applicability of such secondary batteries as power sources for integrated circuit devices on printed circuit boards is increased.
An embodiment of a lithium secondary battery includes an anode using a carbonaceous material, such as graphite, as an active material; a cathode using a lithium transition metal oxide as an active material; a separator; and an electrolyte. The cathode or anode active material of such a lithium secondary battery fundamentally has no electroconductivity. Thus, a conductive network is formed by coating a conductive material onto the surface of spherical active material particles in order to increase electroconductivity.
In addition, in a lithium secondary battery using a metal-based, such as silicon-based, or metal oxide-based anode active material, a method has been developed to reduce the resistance caused by the active material and to resist a large volumetric change of an anode active material during charging/discharging.
In general, a carbonaceous conductive material, particularly amorphous carbon, such as Super-C, is used as a conductive material. However, it is required to form a larger conductive network of an electrode by developing and using a material having higher electroconductivity as compared to carbon.